Lecture 12 Key Concepts/Terms

Why is "prokaryotes" in quotes?

prokaryotes is in quotes because they are a paraphyletic group, not a single, monophyletic group

why do we only spend one day on 2/3s of the tree of life?

scientists currently estimate we only know 1-10% of archaea and bacteria
until about 300 years ago, no one even knew a prokaryote existed

prokaryotes - unicellularity

prokaryotes are typically unicellular

prokaryotes - internal structure

no membrane bounded organelles

prokaryotes - chromosomes

single, circular chromosome
possible plasmids

prokaryotes - cell division

binary fission

prokaryotes - gene transfer

lateral gene transfer

prokaryotes - flagella

simple, singular fiber

prokaryotes - cell wall

ubiquitous (peptidoglycan or pseudomurein)

prokaryotes - size

typically small

eukaryotes - unicellularity

unicellular or multicellular (most are multi)

eukaryotes - internal structure

highly compartmentalized
many organelles

eukaryotes - chromosomes

double membrane bound nucleus with multiple linear chromosomes

eukaryotes - cell division

mitosis

eukaryotes - gene transfer

recombination

eukaryotes - flagella

very complex
9 + 2 structure

eukaryotes - cell wall

in some organisms (no peptidoglycan)

eukaryotes - size

typically larger than prokaryotes

colonial growth

cells aggregate but each performs the same function

filamentous growth

mode of fungal growth

nucleoid region

a non-membrane-enclosed region of the cell where prokaryotic DNA is found

plasmids

small circular DNA molecules that replicate separately from the bacterial chromosome

binary fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

bacterial generation time

some bacteria can reproduce very fast (e coli can reproduce every 20 minutes) while some bacteria can take much longer; these varying generation times help us to understand the variability of different bacteria as we classify them

lateral gene transfer

The transfer of genes from one species to another, common among bacteria and archaea.

peptidoglycan

A type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides.

Pseudomurein

a substance similar to peptidoglycan that is found in the cell wall of archaea

Gram + bacteria/archaea

envelope absorbs crystal violet stain and appears deep purple
have thick layer of peptidoglycan

gram - bacteria/archaea

envelope absorbs safranin and appears pink-red
contain smaller amount of peptidoglycan

how was bacteria classified before genetic analysis?

shape
metabolism
gram + or -
motile or not
photosynthetic or not
unicellular, colony forming or filamentous

pre-DNA analysis of bacteria - shape

coccus, bacillus and spirillum

coccus

a spherical bacterium

bacillus

rod-shaped bacterium

spirillum

spiral shaped bacteria

pre-DNA analysis of bacteria - metabolism

anaerobes and aerobes
photoautotrophs and photoheterotrophs
chemoautotrophs and chemoheterotrophs

obligate anaerobes

organisms that cannot live where molecular oxygen is present

obligate aerobes

require oxygen

facultative anaerobes

Can make enough ATP to survive using using fermentation or respiration.

aerotolerant anaerobes

do not utilize oxygen but can survive and grow in its presence

photoautotrophs

organisms that use light and carbon dioxide as their source of energy
some bacteria and some eukaryotes
chlorophyll
very similar to photosynthesis

photoheterotrophs

organisms that use light and organic compounds as their source of energy
bacteriochlorophyll
makes elemental sulfur
some bacteria

chemoautotrophs

organisms that use inorganic substances and carbon dioxide as their energy source
use chemical bonds
some bacteria, many archaea

chemoheterotrophs (heterotrophs)

organisms that usually use organic compounds (sometimes use inorganic compounds) as their energy source
some bacteria, some archaea, most eukaryotes

hadobacteria

thermophiles that can withstand extremely high temperatures approaching water's boiling point
gram -

hyperthermic bacteria

heat loving bacteria; similar to hadobacteria
gram -

firmicutes

gram-positive cell walls that are thick and strong
some have lost their cell walls
some can form endospores

actinobacteria

gram +
filamentous
many make antibodies
bacteria that attack other bacteria

cyanobacteria

photoautotrophic
can be unicellular, filamentous or colonial
gram -
*photosynthesis *

spirochets

have axial filaments
mobile
gram -
heterotrophs
common pathogens

chlamydias

very small
parasitic
cocci
gram -
two-cell-type life cycles
cannot live long without a host

proteobacteria

most diverse bacterial lineage
gram -
only known species group with all four types of metabolism

metagenomics

DNA from a group of species is collected from an environmental sample and sequenced

Lokiarchaeota

A clade of deep-sea archaea
Have eukaryotic-like genes including cell shape, cytoskeleton formation and cell membrane functioning

Crenarchaeota

most are extremophiles
thermophilic, cryophilic and acidophilic
maintain internal pH

thermophilic

heat loving

cryophilic

thriving at low temperatures

halophilic

salt loving

acidophilic

acid loving

Euryarchaeota

methanogens, halophiles and extreme thermophiles
methane producing bacteria found in animal intestines

methanogens

A group of archaebacteria that produce methane as a by product of their metabolism.

Thermotoga maritima

20% of genes are archaean in origin, even though they are a bacteria; shows that prokaryotes pass genes through lateral transfer between species

Bacillus anthracis

firmicute; causes anthrax

Clostridium botulinum

causes botulism (food poisoning)
forms endospores
firmicute

mycoplasmas

small and lack cell walls
firmicute

streptomyces

actinobacteria
produces streptomycin and other antibiotics

Mycobacterium tuberculosis

causes tuberculosis
actinobacteria

actinomyces

breaks down organic soil
responsible for the "after rain" smell and composting

Treponema pallidum

causes syphilis
spirochete

Berrelia burgdorferi

causes lyme disease
spirochete

Escherichia coli

E. coli
proteobacteria

chlamydia causes what

eye infections and STIs

salmonella

proteobacteria

Vibrio cholerae

causes cholera and plague
proteobacteria

Methanopyrus

deep sea thermal vents
euryarchaeota
thermophile